Blackberry plant named ‘Clark Gold’

ABSTRACT

A new and distinct variety of blackberry plant lacking anthocyanin coloration in it&#39;s various plant parts and having yellow fruit is described. The new variety named ‘Clark Gold’ also has double flowers and enlarged sepals. ‘Clark Gold’ is a sport of the southern dewberry,  Rubus trivalis , and is a biennial, thorny, trailing-vine plant type. The yellow fruit is of medium size and has the sweetness of its wild blackberry relative. It is also a very early variety with low chill requirements.

Rubus trivialis; Variety ‘Clark Gold’.

BACKGROUND OF THE VARIETY

This new variety named ‘Clark Gold’ is the result of a spontaneousmutation of the southern dewberry, Rubus trivialis, a wild blackberryspecies, and was discovered on cultivated land in south Texas (JacksonCounty). The plants of the new variety lack anthocyanin pigmentthroughout all tissues, including the fruit, which is yellow atmaturity, unlike the dark purple fruit of normal blackberries. Thisvariety like most blackberry cultivars has biennial canes with a dormantperiod between first year canes primocanes) and second year canes(floricanes) prior to flowering and fruiting. This new variety isanalogous to ‘Kiwigold’, U.S. Plant Pat. No. 11,313, a yellow-fruitedmutation of the red raspberry variety ‘Heritage’, although occurring ina blackberry species rather than a raspberry species.

Blackberry and raspberry species belong to the same genus Rubus, butfall within different subgenera. The distinguishing morphologicaldifference between blackberries and raspberries is evident when thefruit is picked. In the blackberry the central receptacle (torus) of thefruit remains intact with the fruit when picked, whereas in theraspberry the torus remains attached to the stem resulting in a fruitwith a hollow core. In this respect, ‘Clark Gold’ is a typicalblackberry fruit with a solid core when picked. There are commercialraspberry varieties available with yellow fruit, as well as those withred or black fruit. To date there are no commercial varieties ofblackberry with yellow fruit.

This new cultivar is intended to be marketed as a novel blackberryvariety for home and commercial blackberry fruit production. The fruitin turn can be used for fresh eating or as processed fruit or juice.This variety could also be used as a parent in a plant breeding programto transfer the yellow fruit character and the associated lack ofanthocyanin to other blackberry cultivars. The absence of anthocyaninis, in effect, a gene marker for the yellow fruit character and willfacilitate selection for yellow fruit in a hybridization program. Theabsence of anthocyanin can be detected at a very early stage of theprimocane (first year) while the yellow fruit color is not evident untilmaturity of the fruit in the floricane (second year).

SUMMARY OF THE INVENTION

The present invention relates to a new and distinct variety ofblackberry plant having a yellow fruit and lacking anthocyanin in itsvarious plant parts. This new variety also has double flowers and large,elongated sepals which distinguish it from the wild dewberry, Rubustrivialis, from which it derives. The original plant was a naturallyoccurring whole plant mutation found in a fencerow along County Road 476in Jackson County, Tex. The fencerow was bordering a cultivated field,which had been planted at various times to different crops includingpasture grasses, grain sorghum and various varieties of blackberries.

The original plant of the new variety was propagated asexually by tiplayering in 2000 and 2001. All new plants were phenotypically stable foryellow fruit and the absence of anthocyanin. The asexual reproductionoccurred at the same location in Jackson County, Tex.

This new variety has not been observed under environmental conditionsoutside of southern Texas. The phenotype may vary considerably in otherenvironments, particularly in more northerly climes, although the yellowfruit color and absence of anthocyanin should not be affected.

The new cultivar ‘Clark Gold’ has three distinctive characteristicswhich distinguish it from its progenitor, the southern dewberry, Rubustrivialis, and other blackberry varieties. One of these is major andreadily visible (yellow fruit and yellow green plant), while the othertwo are variations in the floral structure. ‘Clark Gold’ is aspontaneous genetic mutation in which normal anthocyanin pigmentation issuppressed, resulting in vegetative tissues which lack red and purplepigments, and in the fruit which is yellow at maturity. The absence ofanthocyanin and the yellow fruit are presumed to be differentexpressions in the vegetative and fruit tissues, respectively, of thesame genetic trait-ie. suppressed anthocyanin production. The variationsin the floral structure of the new variety are 1) double flower whichhas an increase in the number of petals over the normal corollacomplement of five and 2) larger and elongated sepals as compared to thenormal calyx. The petals of the new variety are also larger, whichcombined with the increased petal number, give the flower a fullerappearance, thus the term “double flower”. These floral abnormalitiesappear to be genetic traits and not symptoms of the Rosette disease,also known as “double blossom”, caused by the fungal pathogenCercosperella rubi, because ‘Clark Gold’ flowers produced fruit ofnormal size and drupelet number unlike Rosette flowers which aresterile.

Like the wild dewberry, Rubus trivialis, from which it derives ‘ClarkGold’ is a trailing vine with numerous curved thorns on the canes,petioles and petiolules. The wild dewberry (WDB) has normal anthocyanincoloration which shows in nearly all its plant tissues as a reddishtinge of varying intensity in the canes, leaves, petioles, petiolulesand thorns. By contrast, ‘Clark Gold’ plants lack anthocyanin and itsvegetation is a light green color to yellow green color with no trace ofred coloration. The primocanes of ‘Clark Gold’ are in the Yellow GreenGroup (146C) of The Royal Horticultural Society Colour Chart while WDBprimocanes are in the Red Purple Group (59A). Anthocyanin coloration innormal plants is especially pronounced in winter foliage, and aroundleaf margins, at the base of petioles and in damaged plant tissues. Thefruit of normal blackberries turn from green to bright red to darkpurple or “black” at maturity. ‘Clark Gold’ berries are dark green whenimmature and turn to yellow, Yellow Group (12B) as they ripen withoutpassing through the red berry stage.

Rubus trivialis, like most blackberry cultivars, has the normal corollacomplement of 5 petals, which are discrete and spatulate (club-shaped).In contrast, ‘Clark Gold’ flowers usually have 6 or more petals, and asmany as 15 petals. The petals are also larger, fan-shaped andoverlapping. Normal blackberry flowers also have a small calyx with 5sepals. ‘Clark Gold’ flowers have a larger calyx with elongated sepals.In all other aspects ‘Clark Gold’ is morphologically identical to itsprogenitor, Rubus trivialis, including fruit characteristics such assize, shape, pH (3.26) and soluble solids (8.7%).

BRIEF DESCRIPTION OF ILLUSTRATIONS

FIG. 1 shows winter foliage of ‘Clark Gold’ (CG) and Rubus trivialis,the wild dewberry(WDB).

FIG. 2 shows primocane leaves (5-foliate) of ‘Clark Gold’ (CG) and Rubustrivialis, the wild dewberry (WDB).

FIG. 3 shows floricane leaves (3-foliate) of ‘Clark Gold’ (CG) and Rubustrivialis, the wild dewberry (WDB).

FIG. 4 shows flowers and petal numbers of flowers of ‘Clark Gold’ (CG)and Rubus trivialis, the wild dewberry (WDB).

FIG. 5 shows shape and size of flowers and calyx of ‘Clark Gold’ (CG)and Rubus trivialis, the wild dewberry (WDB).

FIG. 6 shows yellow fruit of ‘Clark Gold’ (CG) and normal black fruit ofRubus trivialis, the wild dewberry (WDB).

DETAILED DESCRIPTION OF THE NEW VARIETY

The descriptions reported herein are from specimens grown in JacksonCounty, Tex. Color data are presented in Royal Horticultural Society(R.H.S.) Colour Chart designations. Where dimensions, sizes, colors, andother characteristics are given, it is to be understood that suchcharacteristics are approximations of averages set forth as accuratelyas practicable.

Plant:

Size.—Medium, trailing vine with a dense array of thorns.

Growth habit.—Vigorous, sprawling vine forming mats or mounds andscrambling in bushes and fences.

Canes.—Long-running, thorny and glandular hairy. Cane internode lengthat midpoint: 3.87 cm.

Primocane.—Diameter at midpoint: 3 to 5 mm. Color: Yellow Green Group(146C). Thorn length: 4 to 5 mm. Thorn color — Yellow-Green Group(144A).

Floricane (wintercane).—Diameter at midpoint: 2 to 3 mm. Thorn length: 2to 3 mm. Floricane and thorn color — Yellow-Green Group (146B).

Foliage:

Primocane.—Leaves — Medium. Mature compound leaf length 8.6 cm; width8.9 cm. Leaflet: length 4.3 cm; width 2.1 cm; shape narrow-elliptic withacute apex and base; margin incised; abaxial and adaxial surfacesglabrous. Color of adaxial leaflet surface Yellow Green Group (137A);abaxial surface Yellow Green Group (137C). Number of leaflets percompound leaf: 5. Petiole length: 3.2 cm. Petiolule length: 4 to 8 mm.Stipule length: 5 to 7 mm. Color of petiole and petiolule Yellow GreenGroup (146D). Leaf midvein color — Green Group (137A); petiole,petiolule end stipule color — Yellow-Green Group (146C).

Floricane.—Leaves — Small to very small. Mature compound leaf length 4.2cm; width 4.1 cm. Leaflet: length 1.9 cm; width 1.3 cm; shape ellipticwith acute apex, laterals also with a single basal lobe; margin incised;glabrous abaxial and adaxial surfaces. Color of adaxial leaflet surfaceYellow Green Group (137A); abaxial surface Yellow Green Group (137C).Number of leaflets per compound leaf: 3. Petiole length 1.4 cm.Petiolule length: 2 mm. Stipule length: 2 to 4 mm. Leaf midvein color —Green Group (137B); petiole, petiolule and stipule color — Yellow-GreenGroup (146B).

Flowers.—Mostly solitary on erect peduncles, occasionally 2 or 3 onbranched peduncle.

Date of bloom.—First — Julian 75: 50% — Julian 84; Last — Julian 110.

Blossom color.—White. Petal color — White Group (155D).

Reproductive organs.—Stamens — erect, numerous. Pistils — numerous.Pollen — normal. Stamen color — Yellow-Green Group (153A); stigma color— Yellow-Green Group (151D).

Flower diameter.—3.4 cm.

Petal size.—Length — 1.7 cm. Width — 1.9 cm.

Number of petals per flower.—5 to 15, most commonly 7 to 10.

Calyx.—Sepals elongated, apex bluntly serrated. Diameter — 1.9 cm. Sepalcolor — Green Group (137A).

Peduncle length.—5.2 cm. Peduncle color — Yellow-Green Group (146B).

Fruit:

Maturity.—Very early, 10 to 15 days before ‘Brazos’ (non-patented).Average first ripe date is April 19. Average period of ripening is April19 to May 7.

Size.—Medium, average 3.7 g. Length — 2.4 cm. Diameter at base — 1.8 cm.

Shape.—Blocky-ovoid, occasionally spheroid.

Color.—Yellow Group (12B).

Seed size.—Small, 2.4 mg/seed. Seed color — Yellow-Orange Group (18C).

Soluble solids.—8.7%.

pH.—3.28 (as measured by pH meter on a sample of 20 ripe berries).

The variety.—The most distinctive features of the variety are the yellowfruit and the absence of anthocyanin in the various plant tissues. Bothprimocanes and floricanes are thorny, trailing-vine plant types. Themedium-sized fruit has the same sweetness as its wild dewberry relative,Rubus trivialis. Originating in USDA hardiness zone 9, ‘Clark Gold’ isan early ripening, very low chill variety.

I claim:
 1. A new and distinctive variety of blackberry plant,substantially as described and illustrated herein, characterized by (A)having yellow fruit and the absence of anthocyanin coloration in thevegetative and floral parts, (B) double flowers and (C) elongatedsepals.